Given, number of turns per cm in long solenoid, n=20 turns ∕cm=2000 turns ∕m Area of loop, A=
4
π
cm2=
4
π
×104m2 ∆I=3−1=2A ∆t=0.2s ∴ Magnetic field inside the solenoid mm B=µ0nI⋅⋅⋅⋅⋅⋅⋅(i) Magnetic flux linked with loop kept inside the solenoid normal to it, φ=BA =µ0nIA [from Eq. (i)] ∴ According to Faraday's law of electromagnetic induction, magnitude of induced emf is given as |e|=